Keaton stars as a movie projectionist who's learning to be a detective by reading a how-to book. He delivers a box of candy to his girl McGuire only to be upstaged by rival Crane. Back at the movie theater, Keaton falls asleep during the romantic film and dreams that he and his girl are the on-screen couple, still being beset by his rival, although the situations keep changing. He then dreams that he's the famous detective Sherlock, Jr. who must rescue a damsel from villains. Packs an amazing amount into 44 minutes, which came at a transitional point in Keaton's career when he had moved on from two-reel shorts to longer features.